The 28-year-old American’s round included five birdies across his opening eight holes, three of them from beyond 50 feet.
McCarty added four more birdies over his closing five holes to card an eight-under-par 63 and take the clubhouse lead at Quail Hollow Club.
Heavy overnight rain of more than two inches pushed the start back by 90 minutes, while further storms later suspended play with 20 players still needing to complete their first rounds on Friday.
McCarty finished the day with more than 220 feet of made putts and became the first player since PGA Tour distance tracking began to hole three putts from longer than 50 feet in a single round.
“You never really expect to make one of them, let alone three in the span of like five or six holes,” McCarty said.
“I’ve been focused on doing a lot of lag putting the last couple of days out here, just hitting a lot of shots and knowing how long in and I guess that paid off a little bit.”
Four-time Quail Hollow Club champion Rory McIlroy returned a one-under 70 in his first tournament round since capturing a sixth major title at last month’s Masters.
The world number two started his round on the back nine and looked set for a bogey-free but birdie-less card after reeling off 17 straight pars. He finally broke through at the ninth with a 15-foot birdie putt, celebrating by throwing his hands skyward and glancing up to the heavens after the ball dropped.
“I was thinking I can’t remember the last time I played a round of golf and didn’t have a birdie,” McIlroy said. “I was like just try to make one… I thought my chance had passed me by, but nice to see one putt go in there at the last.”
South Korea’s Im Sung-jae, who began on the back nine, made six birdies in his first eight holes and added a 12-foot eagle putt on the par-five seventh to move to seven under with one hole remaining when play was suspended.
As many as five players are tied for third two shots back on five under – Nicolai Hojgaard, Sepp Straka, Kristoffer Reitan, Nick Taylor and Harry Hall.
